Communication: Angle-resolved thermal dissociative sticking of CH4 on Pt(111): Further indication that rotation is a spectator to the gas-surface reaction dynamics

Navin, Jason K.; Donald, Scott B.; Tinney, D. G.; Cushing, Gregory W.; Harrison, I.

doi:10.1063/1.3685833

Cited by 10 publications

(21 citation statements)

References 25 publications

(36 reference statements)

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“…121 We have only investigated the rotationless methane, as experimental evidence suggested that the rotational excitation has a small impact on the DC dynamics. 28,136 The rigid-surface model ignores the motion of surface atoms and energy transfer between the impinging molecule and surface phonons, both representing severe approximations. Jackson and coworkers have investigated these effects extensively and carefully, 115-119 and we follow their approaches to remedy the deficiencies of the model.…”

Section: Reaction Dynamicsmentioning

confidence: 99%

Quantum dynamics of polyatomic dissociative chemisorption on transition metal surfaces: mode specificity and bond selectivity

et al. 2016

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Dissociative chemisorption is the initial and often rate-limiting step in many heterogeneous processes. As a result, an in-depth understanding of the reaction dynamics of such processes is of great importance for the establishment of a predictive model of heterogeneous catalysis. Overwhelming experimental evidence has suggested that these processes have a non-statistical nature and excitations in various reactant modes have a significant impact on reactivity. A comprehensive characterization of the reaction dynamics requires a quantum mechanical treatment on a global potential energy surface. In this review, we summarize recent progress in constructing high-dimensional potential energy surfaces for polyatomic molecules interacting with transition metal surfaces based on the plane-wave density functional theory and in quantum dynamical studies of dissociative chemisorption on these potential energy surfaces. A special focus is placed on the mode specificity and bond selectivity in these gas-surface collisional processes, and their rationalization in terms of the recently proposed Sudden Vector Projection model.

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Section: Reaction Dynamicsmentioning

confidence: 99%

Quantum dynamics of polyatomic dissociative chemisorption on transition metal surfaces: mode specificity and bond selectivity

et al. 2016

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“…25) and Doser 2 are compared with the d-PMMT simulation in Fig. 4 in an amplitude-scaled manner that highlights the angular variations.…”

Section: A Dissociative Chemisorptionmentioning

confidence: 99%

“…25 Further averaging over the angular distribution of the incident molecules yields the thermal dissociative sticking coefficient,…”

Section: B Thermal Associative Desorptionmentioning

confidence: 99%

“…10,[20][21][22][23][24] A full dimensional quantum dynamical model recently developed by Jackson and Nave for methane on Ni surfaces 15,16 treats parallel translations using a sudden approximation to average over surface impact sites and treats rotational motions adiabatically. Recent comparisons 19,25 of the reactivity of methane incident on Pt(111) from effusive molecular beams and from supersonic molecular beams with very different molecular rotational energy distributions, characterized by different rotational temperatures, concluded that molecular rotations can be approximated as spectator degrees of freedom within a microcanonical model. This discernment was possible because molecules prepared in an effusive molecular beam have thermal energy distributions whose gas temperature, T g = T t = T v = T r , is shared by all molecular degrees of freedom, 26 whereas methane molecules prepared in a supersonic beam with nozzle temperature T N suffer negligible vibrational cooling, T v = T N , but substantial rotational cooling, T r = 0.1 T N , due to inter-molecular collisions that occur during the supersonic expansion.…”

Section: Introductionmentioning

confidence: 99%

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Methane dissociative chemisorption and detailed balance on Pt(111): Dynamical constraints and the modest influence of tunneling

Donald

Navin

Harrison

2013

The Journal of Chemical Physics

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A dynamically biased (d-) precursor mediated microcanonical trapping (PMMT) model of the activated dissociative chemisorption of methane on Pt(111) is applied to a wide range of dissociative sticking experiments, and, by detailed balance, to the methane product state distributions from the thermal associative desorption of adsorbed hydrogen with coadsorbed methyl radicals. Tunneling pathways were incorporated into the d-PMMT model to better replicate the translational energy distribution of the desorbing methane product from the laser induced thermal reaction of coadsorbed hydrogen and methyl radicals occurring near T(s) = 395 K. Although tunneling is predicted to be inconsequential to the thermal dissociative chemisorption of CH4 on Pt(111) at the high temperatures of catalytic interest, once the temperature drops to 395 K the tunneling fraction of the reactive thermal flux reaches 15%, and as temperatures drop below 275 K the tunneling fraction exceeds 50%. The d-PMMT model parameters of {E0 = 58.9 kJ/mol, s = 2, η(v) = 0.40} describe the apparent threshold energy for CH4/Pt(111) dissociative chemisorption, the number of surface oscillators involved in the precursor complex, and the efficacy of molecular vibrational energy to promote reaction, relative to translational energy directed along the surface normal. Molecular translations parallel to the surface and rotations are treated as spectator degrees of freedom. Transition state vibrational frequencies are derived from generalized gradient approximation-density functional theory electronic structure calculations. The d-PMMT model replicates the diverse range of experimental data available with good fidelity, including some new effusive molecular beam and ambient gas dissociative sticking measurements. Nevertheless, there are some indications that closer agreement between theory and experiments could be achieved if a surface efficacy less than one was introduced into the modeling as an additional dynamical constraint.

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“…[10][11][12][13][14][15][16][17] On the other hand, the rotation of CH 4 was found to be largely a spectator. 18,19 The mode selectivity and the related bond selectivity, 20 strongly suggest that the reaction cannot be described by statistically inspired models, such as the transition-state theory, 21 which assume that different forms of energy should contribute equally to overcome the reaction barrier. In other words, the dynamics on the multidimensional potential energy surface (PES) is important.…”

Section: Introductionmentioning

confidence: 99%

Effects of reactant internal excitation and orientation on dissociative chemisorption of H2O on Cu(111): Quasi-seven-dimensional quantum dynamics on a refined potential energy surface

Jiang

Xie

et al. 2013

The Journal of Chemical Physics

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To understand the influence of reactant internal excitation and orientation on the dissociative chemisorption of water on Cu(111), a quasi-seven-dimensional quantum dynamics study has been carried out on a refined potential energy surface (PES). The new PES was modified in the asymptotic region to allow an accurate characterization of the H(2)O ro-vibrational levels. The mode selectivity of the reaction was reexamined on the new PES and found to be consistent with our earlier work. To rationalize the observed mode selectivity, a vibrationally adiabatic reaction path model was determined on this PES. Furthermore, the reactivity for various rotationally excited H(2)O was investigated. It is shown that even low rotational excitation in H(2)O can either enhance or inhibit the reaction and the reactivity depends on the orientation of the impinging molecule.

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Communication: Angle-resolved thermal dissociative sticking of CH4 on Pt(111): Further indication that rotation is a spectator to the gas-surface reaction dynamics

Cited by 10 publications

References 25 publications

Quantum dynamics of polyatomic dissociative chemisorption on transition metal surfaces: mode specificity and bond selectivity

Quantum dynamics of polyatomic dissociative chemisorption on transition metal surfaces: mode specificity and bond selectivity

Methane dissociative chemisorption and detailed balance on Pt(111): Dynamical constraints and the modest influence of tunneling

Effects of reactant internal excitation and orientation on dissociative chemisorption of H2O on Cu(111): Quasi-seven-dimensional quantum dynamics on a refined potential energy surface

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